One basic rule is to never stop moving forward.
One strike or kick should always be connected to a step forward.
If you're relatively new (<6 months), try that in shadowboxing.
It's quite hard in the beginning.

You need to work hard at becoming aggressive in sparring, its easily the most important thing in a fight. I've seen many, many technically better, stronger and fitter people lose to more aggressive opponents.

Just don't mistake aggression for anger or wild swinging.

"Boxing is the art of hitting an opponent from the furthest distance away, exposing the least amount of your body while getting into position to punch with maximum leverage and not getting hit."
Kenny Weldon

I think a lot of people have been brainwashed by our society into feeling that aggression is wrong. I am constantly surprised by the amount of teenagers coming through our classes who can't hit a pad like they want to hurt it let alone another person. Some women have it the worst, its like you have to get through twenty years of conditioning before you can teach them how to hit something hard.

It can definitely be improved, I don't know about through doing techniques though. The only way I've seen it is through fighters actively trying to be more aggressive in sparring each day until it becomes a habit.

"Boxing is the art of hitting an opponent from the furthest distance away, exposing the least amount of your body while getting into position to punch with maximum leverage and not getting hit."
Kenny Weldon

What do you mean by defensive? Are you a counter-fighter? Do you mostly block and take it? Need more understanding of what you have in mind before I can generate a cogent response.

Yes. I usually let the other person attack me first.

Originally Posted by Hiro Protagonist

How long do you train, and in which discipline were you criticized?

In Karate, it's a totally different game than in boxing.

One basic rule is to never stop moving forward.
One strike or kick should always be connected to a step forward.
If you're relatively new (<6 months), try that in shadowboxing.
It's quite hard in the beginning.

We usually spar for half hour sessions, even though I wished we sparred more often.

I took Isshinryu for 4 years before switching to Kyokushin, where in Isshinryu we sparred kickboxing style (except we were allowed to kick the legs and groin as well), and my teacher there noticed my lack of aggression.

I was told to use the Sabaki method, of trying to use angles rather than try to meet face to face or trying to back up.

I just notice today in Kyokushin, I lack aggression and need to learn how to set up combinations.

If you guys do combinations, do you still commit to them even though they don't go as planned?

I just feel I can go a lot harder in sparring, but I'm afraid of hurting the other guys. I just crippled someone with an accidental nut shot the other day (he is fine, but I felt bad). My thigh kicks are definitely aggressive enough (ramble).

Because of the fact that my style (not so technical) is heavily reliant on aggression, I often get charged with helping noobs suffering real aggression issues (ie. not being able to even hit a pad full force).
in concurrance with Sang's point, and from what I've experienced in trying to encourage people, including my heavily bullied brother to become more agressive, the most effective way seems to be to take it as a gradual experience of encouraging aggression until it becomes a habit.

To put it in perspective a little, my brother has been getting his ass kicked pretty much constantly since he started school, despite holding a first dan in shotokan (about 5'3 115lbs). The combination of us going to different schools, and the age difference between me and the kids bullying him, meant there wasn't much I've been able to do in terms of intervention. Through encouragement and some basic boxing coaching however, he's really started to get some 'balls', and a little while ago actually gave his first ass kicking to someone for throwing a milkshake bottle at his head.

I understand that the particular situation is not relative to combat sports directly, but the ability to build aggression is relative imo.

"The hero and the coward both feel the same thing, but the hero projects his fear onto his opponent while the coward runs. 'Fear'. It's the same thing, but it's what you do with it that matters". - Cus D'Amato

If you guys do combinations, do you still commit to them even though they don't go as planned?

YES. Sounds cheesy, and is too generalizing, but never ever back down from a technique. If your body loses the impulse - if you cut it by stopping - that is likely to be an opening in your own defense.

Originally Posted by Smoke

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I just feel I can go a lot harder in sparring, but I'm afraid of hurting the other guys.

Then do so. Every punch, every kick goes with a step towards the opponent. Try that. You will probably get wasted the first few times, but you will learn that way to engage your opponent.

Also, what Sang said. You are there to fight, and so is your training partner. Going soft on them won't help them, nor you.